Commercial creaseproofing of cellulosic fabrics began ca. 1926, with the Tootal, Broadhurst, Lee (TBL) method. In the early 1960's, significant advances were developed as taught in U.S. Pat. No. 3,049,446 by using combinations of urea, glyoxal, and formaldehyde to treat fabrics in one step under acidic conditions. This technology was the first to achieve wrinkle resistance with acceptable strength retention and durability. dimethyloldihydroxyethylene urea ("DMDHEU") remains the most widely used creaseproofing agent in the United States, and indeed the world, for cellulosic fabrics today.
However DMDHEU has the disadvantage of high residual parts per million formaldehyde on the fabric after curing. Other advancements in this area were the addition of diethylene glycol to DMDHEU by Andrews et. al., the use of glycolated DMDHEU in U.S. Pat. No. 4,396,391 and the work of Pacifici in U.S. Pat. No. 5,268,502 for reducing formaldehyde in DMDHEU based systems.
DMDHEU, methylated DMDHEU and glycolated DMDHEU all require catalysts to achieve crosslinking in cellulosic fabrics during the curing process. Manufacturers of these creaseproofing chemicals recommend 20-30% catalyst on the weight of the reactant. The combination of the effect of crosslinking, heat and catalyst causes severe strength loss in the cellulosic fabric. This is especially true for all cotton fabrics and cotton blend (50% cotton and above) fabrics.
Recently, apparel fabrics manufacturers of 100% cotton have treated fabric with high levels of creaseproofing agents and have enjoyed favorable consumer acceptance under the description "wrinkle free." While these have achieved market acceptance, the physical performance of the fabrics has been marginal in the area of strength and to some extent the "wrinkle free" properties. There is substantial variation in the wash appearance rating as measured by AATCC Method 124. The term "wrinkle free" has been generally defined as having a DP rating of 3.5 or above when measured by the AATCC Method 124. Many of the apparel fabrics sold as "wrinkle free" 100% cotton actually have DP ratings below 2.5.
There is a need in the art for wrinkle free fabrics that have improved strength over the fabrics currently being manufactured. There is also a need for fabrics which meet the 3.5 wrinkle free standard.